Drafting machine counterbalance



Oct. 5, 1943. J. w. HARRIMAN DRAFTING MACHINE COUNTERBALANGE 2 Sheets-Sheet 1 Filed June 19, 1941 Oct. 5, 1943.

J. W. HARRIM AN DRAFTING MACHINE COUNTERBALANCE 1941 2 Sheets-Sheet 2 Filed June 19 FM mm WW W M W W W 0.2 I FTTZZ? The counterweight rail'..6 has one end connected with the bracket 9 by a pivot device l3.v

In the arrangement shown in Fig. 2, the opposite end of the rail 6 extends for sliding movements through a supporting. guide I4 having a pivot I5 mounted in a bracket l6 attached to a cross member I! of the drawing table. Rollers l8 rotatively support the counterweight 5 to facilitate its movement along the rail 6 and minimize friction. V fl In Fig. 5, the lower end of the rail '6 extends through a slot [9 formed in a bracket 20. attached directly to the underside of the drawing board I. The rail 6 may be secured at any angle of inclination with respect to the drawing'board and maintained inconstant'relationship thereto by a clamping device comprising a shoulder 2| on the rail 6 abutting against the bracket 20 and fixed relationship with respect to the drawing board I.

By loosening the nut", the rail 6 may be movedto any other angle of inclination within the length of theslot l9 and secured. in

- that position by tightening the nut 22. Also, the

rollers l8 may be omitted from thecounterweight 5, leaving the coutnerwei'ght mounted directly on the rail 6 for sliding movements.

In Figs. 8 and 9, the counterbalance mechanism is mounted for lateral movements along "the drawing board with thehead 4 or the draftingmachine. In this arrangement, the pulley 8" ries two laterally spaced rollers 23 operating against a rail 24 attached to theupper edge of the drawing board I, and a pair of laterally spaced rollers 25 operating on a rail 25 attached .to the upper marginofthe drawing board .I.

'is rotatively supported in a bracket 9' which car,- I movements from a horizontal position'to various The counterweightrail -B haslits upper end attached to the bracket 9' and its lower end equipped with a roller 2'! operating along a rail 28 supported by the'understructure' of the table parallel with the rails 24 and 26.. The counterweight 5 is connected with the head. 4. of the drafting machine by acordjl' passingbetween in Fig. 2 and. be provided with rollers to operate along the counterweight rail 6, or may slide along said rail, as desired. a I In the variation ,shownin .Fig. 10, a bracket 30 supports a pair .of rollers 3| operating, against a rail 32 attached to the upper edgev of the drawing board I, and'also supports a pair of laterally spaced rollers 33 operating on a rail34 attached to the underside of the drawing board. The.

rails 32 and34 are parallel with each other as,

of course, are the rails M, and 26. Inthisform of the invention, the'flcounterweight rail 35-has its upperend rigidly attachedto the bracket 30 and its lower= end free from anysupporting elementand provided with an abutment 36 for the counterweight 31 mounted on said rail. 'In this form of the device, the cord 1 has one end attached to the head 4 of the drafting machine and its opposite end attached to the bracket 30 by a fastener 38. This cord passes between guide rollers 39 on said bracket around the pulley 8' and around a roller 40 rotatively supported by the counterweight 31. In this form of the invention, the counterweight mechanism may move .laterallyalong with the drafting machine the same as" in the construction shown in Fig. 9.

Obviously, the rail 35 can be attached to a bracket such as the bracket 9 constructed for I rigid attachment to the drawing board.

From the foregoing, it is apparent that in either embodiment of the invention, the tendency of the drafting machine to slide downwardly along the drawin board when the latter is tilted mm horizontal to any inclined position is re sisted by the counterweight. The counterweight constitutes a variable force acting to counterbalance the weight of the drafting machine so that'the drawing board'may be tilted' rapidly to any inclined position without displacing the drafting machine and, at the same time, leaving the. drafting machine freely movable over the surface of the board. In the arrangement shown in Figs: 1 to 5, the counterbalancev mechanism is in a fixed position whereas, in Figs. 8,9 and 10,

' the'counterbalance mechanism accompanies the.

drafting machine in its lateral movements along the drawing board.

The invention may be varied in other respects thanjn-those specifically shown and described, and I'conte-mplate such variations in the-form and structure of the parts and their relative arrangement as may be'needed. Such variations may be made without departure from the nature and principle of the invention.- I'c'laim: 1

1, In -a drawing board supported for swinging per end pivoted to said bracket, a guide for the lower end of said guide rail for supporting the same: in different angular positions with respect to the drawing board according to the angular positions of the latter, a counterweight for the head of said drafting machine mounted on said guide rail, a cord attached to said bracket and to saidhead of the drafting machine, means forengaging. an intermediate, portion of said cord with said counterweight .for counterbalancing said head ofv the drafting machine, and guide rollers on. said bracket engaging and guiding said cord during movements thereof by said head. of the drafting machine.

2. In a drawing board supported for pivotal swinging movements from a horizontal position to any desired angle of inclination from said horizontal position and having a drafting machine attached toand provided with ahead mounted for free movements over said'drawing board; abracket attached to the upper portion of the drawing board, a counterweight guide rail having one end pivoted to said bracket anddiverging downwardly from the underside of the drawing board, a counterweight mounted for movements along said rail, a pulley supported by said counterweight, guide pulleys supported by said bracket, and a cord engaging all of said ens evo pulleys and having one end attached to said bracket. and the opposite; end detachably secured to saiiihead of the drafting machine andiholding said head from accidental displacement along the-drawm g board when'said board'is moved to angular positions from the. horizontal.

from the underside of the drawing board, a sup-- port for the lower end of said rail, a 'counterweight, for saidhead of the drafting machine mounted for movements. along said guide rail, a pulley supported by said counterweight, guide pulleys mounted onsaidbracket, and a cord attached to said bracket and extending downwardly therefrom around said pulley on said; counter weight and also extending upwardly therefrom and engaging said pulleys on said bracket and having one end detachablysecured tosaid head of the drafting machine.

4. In a drawing board supported for pivotal swinging movements from a horizontal position to any desired angle of inclination from said horizontal'position, andhaving a drafting machine attached to and p-rovided'with a head mounted for free movements over said drawing board; a bracket attached tothe upper edge of said drawing boardguide pulleys mounted on said bracket, a counterweight guide rail having one end pivoted'to said bracket, 3, pivoted guide for the opposite end of said guide rail below the drawing board, a counterweight mounted for movements along said guide rail'betwe'en said bracket and said guide, a pulley supported by said counterweight, and a cord attached to said bracket and looped around said last named pulley and engaging said pulleys on said bracket and having one end detachably secured to said head of the drafting machine. I

5. In av drawing board supported for pivotal swinging movements from a horizontal position to any desired angle of inclination irom said horizontal position, and having a drafting machine attached to and provided with a head mounted for free movements over said drawing heard; a bracket attached to one edge of said drawing board, pulleys mounted on said bracket, 3 counterweight guide rail havihg one end pivoted to said bracket, a support for the opposite end of said. guide rail below the drawing board,

- rail having one end supported by said bracket; a

supportffori the; :oppositeend of: said guide rail leaving-1 said 'raii free'tosmofve laterally 'withsaid bracket; acounterweight mounted ion movement's along said rail between said. braeketr and said support; pulleysl supportedihy said bracket and by said counterweight respectively; a cord "attached t said bracket and looped around "said pulley on said counterweight andengaging said pulleys on said bracketend means detachahly securing said cord to said headwofthe drafting machine. o a

"Z; In a drawing boar-d supported'for' pivotal swinging movements from a horizontal position to any desired angle of inclination'from said horizontal position, and ha vin a. drafting machine attached to and provided with a head mounted for free. movement over said drawing board; aco-un- 17931333511166 mechanism supported for lateral movements alon one edge ofysaid drawing-board, and means connecting said" counterbalance mechanism with said head of *thedraftinfg machine where said head from accidental displacerirent when the drawing board is horizontal position.

8.. Iii-"a drawing board sup-ported for pivotal swinging movements from "a horizontal position to desired angle of inclination from said horizontal. position, and having 'a idrafting machine; attached to and provided with a head mounted for free movements over said drawing boa-rd; a "counterbalance mechanism for said drafting machine, devices supporting said counterbalancemechanism ,for lateral movements along; the drawing hoardin accompaniment with said drafting rizachiria'dnd a' cord connecting said coimterba lance' mechanism with said drafting' machine for holding said machine from acci dental displacementvwhen the drawing board is moved from horizontal position.

9. In 'a drawing beard supported for pivotal swinging movements from a horizontal position means cooperating with said support for holding said guide rail at diiierent angles of inclination relative to said drawing board, a'counterweight mounted for movements along said guide rail between said bracket and said support, a pulley mounted on said counterweightja cord looped around said last named pulley and engaging said to 'anydesired' anglefoi inclination from said horizontal position, and having a drafting machine necting said counterbalance m'echani'sm with said head o'ithe drafting machine;

10. In a. drawing board supported for pivotal swiing'ing movement-s from a horizontal position to any desired angle or inclination from said hori;

dental position, "and "having "a drafting machine attached to and provided with a head moimted ll. Ina drawing board tast es understrucr ture and having a horizontal pivot supporting saidhoard on said' understructure for swinging movements about 'ahorizontal axisirom'a'hoi'izontal position to various angles of inclination from said position, and also havin a drafting moved from board is moved machine attached to said board and provided with a head movably mounted upon said board; a guide rail supported by and at the underside of the drawing boardand extending forwardly from the rearrportion of said board and transversely of the plane of said'horizontal pivot, a countering an understructure pivotally. supporting said drawing board for swinging movements about a horizontal axis to various angles of inclination and thereby raising and lowerin said front and rear sides, and also having a drafting machine attached to said board and provided with a, head movably mounted upon said board; a guide rail extending transversely of the plane of said horizontal axis, meansfor supporting said guide rail spaced downwardly from the underside of the drawing board, a counterweight for said drafting machine supported for movements along said rail in accompaniment with the movements of said drafting machine relative to said board, a cord having one end rigidl attached with respect to said board and the opposite end attached to said head of said drafting machine and having an intermediate portion movably. engaging and supporting said counterweight, and a pulley supported by the rear side of said drawing board for rotation about a horizontal axis and engaging and supporting said cord between said head and said counterweight.

13. In a drafting machine having a drawing board provided with front and rear sides and havin an understructure pivotally supporting said drawing board for swinging movements about a horizontal axis to various angles of inclination and thereby raising and lowering said front and attached to said board and provided with a head movably mounted upon said board; a counterweight for said drafting machine, means for supporting and guiding said counterweight for movements forwardly and rearwardlybelow the drawing board transversely of said axis andcomplementary to any movements of said head above the drawing board, a cord having one end rigidly attached to the rear side of said drawing board andthe opposite end attached to said head of the drafting, machine, an anti-friction device connecting the intermediate portion of said cord with said counterweight for moving said counterweight when said head is moved above the draws ing board as aforesaid, and a pulley supported by the rearportion ofsaid drawing board for rotation about a horizontal axi and-engaging said cord between said head and said anti-friction device for supporting and guiding said cord during movementthereof by said head.

14. In a draftin machine-having a drawing board provided with front and rear sides and having an understructure pivotally supporting said drawing board for swinging movements about a horizontal axis to various angles of inclination and thereby ,raising and lowering'saidv front and rear sides, and also having adrafting machine attached to said board and provided with a head movably mounted upon said board; a guide rail below said drawing board and extending forwardly transversely of the plane of said horizontal axis and inclining downwardly and forwardly from said drawing board, means attached to said drawin board for supporting and moving said guide rail with said drawing board, a counterweight for said drafting machine supported by and for movements along said rail in accompaniment with the movements of said drafting machine relative to said. board, a pulley supported by said counterweight, a cord engaging said pulley and having one end connected with said drawing board and the opposite end attached to said head, and a series of pulleys supported at the rear side of said drawing board supporting and preventing lateral displacement of said cord between said first pulley and said head.

15. In a draftin machine having a drawing board provided with front and rear sides and having an understructure pivotally supporting said drawing board for swinging movements about a horizontal axis to various angles of inclination and thereby raising and lowering said front and rear sides, andalso having a, drafting machine attached to said board and provided with a head movably mounted upon said board; a bracket supported by said drawing board at the rear side thereof, a counterweight guide rail having its rear end attached to and supported by said bracket, a guide for the forward end of said guide drafting machine, and a series of guide rollers rear sides, and also having a drafting machine I on said bracket engaging and guiding and preventing lateral displacement of said cord during movements thereof b said head of the drafting machine. v

16. In a drafting machine having a drawing board provided with front and rear sides and having an understructure pivotally supporting said drawing board for swinging movements about a horizontal axis to various angles of inclination and thereby raising and lowering said front and rear sides, and also having a drafting machine attached to said board and provided with a head movably mounted upon said board; a bracket supported by said drawing board at the rear side thereof, a guide rail attached to said bracket and diverging downwardly and forwardly from and below the drawing board, a counterweight for said drafting machine supported for movements along said rail in accompaniment with the movements of said drafting machine relative to said 

